package org.apache.maven.model.building;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import org.apache.maven.model.DependencyManagement;
import org.apache.maven.model.Model;

/**
 * Describes a tag used by the model builder to access a {@link ModelCache}. This interface
 * basically aggregates a name and a class to provide some type safety when working with the
 * otherwise untyped cache.
 *
 * @author Benjamin Bentmann
 * @param <T> The type of data associated with the tag.
 */
interface ModelCacheTag<T> {

  /**
   * Gets the name of the tag.
   *
   * @return The name of the tag, must not be {@code null}.
   */
  String getName();

  /**
   * Gets the type of data associated with this tag.
   *
   * @return The type of data, must not be {@code null}.
   */
  Class<T> getType();

  /**
   * Creates a copy of the data suitable for storage in the cache. The original data to store can be
   * mutated after the cache is populated but the state of the cache must not change so we need to
   * make a copy.
   *
   * @param data The data to store in the cache, must not be {@code null}.
   * @return The data being stored in the cache, never {@code null}.
   */
  T intoCache(T data);

  /**
   * Creates a copy of the data suitable for retrieval from the cache. The retrieved data can be
   * mutated after the cache is queried but the state of the cache must not change so we need to
   * make a copy.
   *
   * @param data The data to retrieve from the cache, must not be {@code null}.
   * @return The data being retrieved from the cache, never {@code null}.
   */
  T fromCache(T data);

  /**
   * The tag used to denote raw model data.
   */
  ModelCacheTag<ModelData> RAW = new ModelCacheTag<ModelData>() {

    public String getName() {
      return "raw";
    }

    public Class<ModelData> getType() {
      return ModelData.class;
    }

    public ModelData intoCache(ModelData data) {
      Model model = (data.getModel() != null) ? data.getModel().clone() : null;
      return new ModelData(data.getSource(), model, data.getGroupId(), data.getArtifactId(), data.getVersion());
    }

    public ModelData fromCache(ModelData data) {
      return intoCache(data);
    }

  };

  /**
   * The tag used to denote an effective dependency management section from an imported model.
   */
  ModelCacheTag<DependencyManagement> IMPORT = new ModelCacheTag<DependencyManagement>() {

    public String getName() {
      return "import";
    }

    public Class<DependencyManagement> getType() {
      return DependencyManagement.class;
    }

    public DependencyManagement intoCache(DependencyManagement data) {
      return (data != null) ? data.clone() : null;
    }

    public DependencyManagement fromCache(DependencyManagement data) {
      return intoCache(data);
    }

  };

}
